package com.gzyj.flink.dto.utils;

/**
 * @author lhj
 */
public class ToolUtils {

    private final static double EARTH_RADIUS = 6378.137; //地球半径

    private static double rad(double d) {
        return d * Math.PI / 180.0;
    }

    /// <summary>
    /// 单位千米
    /// </summary>
    public static double GetDistance(double lng1, double lat1, double lng2, double lat2) {

        double radLat1 = rad(lat1);

        double radLat2 = rad(lat2);

        double a = radLat1 - radLat2;

        double b = rad(lng1) - rad(lng2);

        double s = 2 * Math.asin(Math.sqrt(Math.pow(Math.sin(a / 2), 2) +

                Math.cos(radLat1) * Math.cos(radLat2) * Math.pow(Math.sin(b / 2), 2)));

        s = s * EARTH_RADIUS;

        s = (s * 10000) / 10000;

        return s;

    }
}
